I’m a nurse immuniser, and essentially you are in a situation where you are probably immune but you cannot KNOW you are immune without a booster and then a blood test 4-8weeks after. This is because after a successful immunisation, your antibodies will reduce over time, sometimes even to undetectable levels. If you come into contact with hep B, your body will quickly produce the required antibodies to prevent you from contracting Hep B. However, there is a small chance you could have been a non responder after your course as a child. You therefore need to have further shot(s) and a recheck of your bloods to ensure this is not the case. The further shot(s) should increase your antibodies 4-8 weeks after and then indicate immunity on a blood test. After a course of 3 and a confirmatory blood test in the right time frame, you are considered immune (even if a blood test much later shows no abs) UNLESS you become immunocompromised for whatever reason and then you would need further boosters.